First Total Syntheses of 1,3-Disubstituted β-Carboline Alkaloids, Dichotomide I and Marinacarbolines A-D
摘要:
The first total syntheses of dichotomide I (1), and marinacarbolines A-D (3-6) were achieved in four steps from methyl 1-chloro-beta-carboline-3-carboxlyate (9), which was previously used as a synthetic intermediate of dichotomine C. The required compound 9 was prepared in a six-step sequence including a microwave-assisted thermal electrocyclic reaction of a 1-azahexatriene system.
(S)-(–)-Dichotomine A and its enantiomer were synthesized from the key intermediate, methyl 1-(1-hydroxyethyl)-β-carboline-3-carboxylate, by enantioselective esterification with Lipase QLM. The first totalsynthesis of (+)-dichotomide II and its enantiomer were also achieved from (S)-(–)-dichotomine A methyl ester and its enantiomer. The absolute configuration of the stereogenic center of the reported
(S)-(-)-Dichotomine A 及其对映体是由关键中间体 1-(1-羟乙基)-β-咔啉-3-羧酸甲酯通过脂肪酶 QLM 的对映选择性酯化合成的。(+)-dichotomide II 及其对映体的首次全合成也是由 (S)-(-)-dichotomine A 甲酯及其对映体实现的。报告的 (+)-dichotomide II 的立体中心的绝对构型被确定为 R。